Mesa Powerhouse 1x15 -- how is it?

I'm considering getting a Mesa Powerhouse 1x15 cab. I've already tried one of them and it sounded OK to me but I'm not that great at auditioning cabs. I know it's not like a typical 1x15 cab, it's a small enclosure that appears to be a sealed design. How do these cabs perform?

I have a power house 15 under a power house 4 x 10 driven by a m pulse 600 .
I am having problems with the 15 right now .Actually its the second time I have had trouble with it . The first time after about an hour worth of play it died ! Mesa covered it though (new speaker in about a week or so ) Now the replaced speaker rattles likes somthing s loose inside of it .I tilt the cabinet back and it goes away .It i still under warranty so Im gonna call mesa this week . I
have heard nothing but good things about their customer support though. I just hope I have gotten a couple of lemons .I like the cabinet alot but this is starting to bring me down .
Also it is a ported cab . They come in two versions one with a horn and another without.They are built like tanks (tank tough not heavy )And the removable casters are great I would like to put them on all my gear .

I had one for about a month, and loved it. I'm thinking of buying it, but have to try some other cabs first. So far it's ahead of the pack. I had a long discussion with a couple other members about this cab. Look it up! "Volume by cab efficiency" or something like that? I loved the tone above the rest, it was tight for a 15 and plenty loud too. Also if anybody knows it's db rating please post it. Apperently Mesa doesn't let people know because each cab is hand tuned, so I guess this makes a difference? It sounds absolutly deadly with a 2x10 on top!

my pwr house 15 is back in true form . Ironic as it may be the thing rattling inside of my speaker was a small metal screen used to keep stuff from getting inside my speaker ! I talked to customer support (they were way cool btw )I was told to remove the speaker to see if anything was actually in it and what do you know . I removed the guilty party and now Im back in business .
After reading my first post it may sound like I dont like this cab . I do .I was just stressed out . It sounds great to my ears .Especially for a single 15 (I have the model with no horn )
And after all this all I can sayis trust your own ears .One mans junk is another mans dream tone !

IMO, the Powerhouse cabs are not as good as the older Diesel or RoadReady cabs. I haven't played any RR cab, but supposedly they sound better than the Diesels, which I think sound better than the PH's (I have two Diesels).